Process for the preparation of a reinforced article

Abstract

The invention is directed to a process for the preparation of a reinforced article which comprises the step of molding a molding composition comprising pellets into the article at an elevated temperature, wherein each of the pellets has an axial length and comprises a core and a sheath around the core, wherein the core comprises an impregnating agent and a multifilament strand comprising glass fibers each having a length substantially equal to the axial length of the pellet and substantially oriented in the axial length of the pellet, wherein the sheath comprises a thermoplastic polymer; and wherein the molding composition further comprises a filler.

Claims

1. A process for the preparation of a reinforced article comprising: molding a molding composition comprising pellets into the article at an elevated temperature, wherein the elevated temperature is a temperature at which the molding composition has enough flowability to be molded, wherein each of the pellets has an axial length and comprises a core extending along the axial length and a sheath around the core, wherein the core comprises an impregnating agent and a multifilament strand comprising glass fibers each having a length substantially equal to the axial length of the pellet and substantially oriented in the axial length of the pellet, wherein the amount of glass fibers in the multifilament strand is 30-50 wt % based on the weight of the molding composition, wherein the sheath comprises a thermoplastic polymer, wherein the thermoplastic polymer is a propylene homopolymer or a propylene copolymer; and wherein the molding composition further comprises a filler and wherein the molded composition has an isotropic E-modulus of at least 5000 MPa as determined according to ISO527/1B at 23° C.

2. The process according to claim 1, wherein the filler is present in the sheath of the pellet.

3. The process according to claim 1, wherein the filler comprises talc particles or glass fibers.

4. The process according to claim 1, wherein the molding step involves injection molding.

5. The process according to claim 1, wherein the molding composition comprises 0.5-25 wt % of the filler based on the weight of the molding composition.

6. The process according to claim 1, wherein the amount of filler is 1-20 wt % based on the weight of the molding composition.

7. An article obtainable by the process according to claim 1.

8. The article of claim 7, wherein the article is an automotive part.

9. The process of claim 1, wherein the isotropic E-modulus is at least 6000 MPa as determined according to ISO527/1B at 23° C.

10. The process of claim 1, wherein the viscosity of the impregnating agent is less than 100 Centistokes.

11. The process of claim 1, wherein the impregnating agent is present in an amount of 0.05 to 6 weight percent based on the total weight of the molding composition.

12. The process of claim 1, wherein the elevated temperature is above the melting point of the thermoplastic polymer that is present in the sheath of the pellets.

13. The process of claim 1, wherein the elevated temperature is 150-500° C.

Description

EXAMPLES

Testing Methods

(1) Injection molding of samples for measuring isotropic strength and isotropic modulus was done on an Arburg 320T using a mould with dimensions of 270×310×3 mm. The injection molding machine has 8 temperature zones (220, 220, 230, 230, 235, 235, 240, 240° C.). Injection pressure is 800 bar and backpressure is 150 bar.

(2) Specimen types as defined by ISO 527/1B were machined from plates obtained or cut by water jet, taking care to obtain smooth specimen edges.

(3) Tensile testing was carried out according to ISO 527/1B at 23° C.

(4) Test speed for determining E-modulus was 1 mm/min and tensile strength and elongation at break was determined at a test speed of 5 mm/min.

(5) At least 6 specimens per orientation (0°, 45° and 90°) were tested.

Example 1

(6) A molding composition was prepared by mixing pellets comprising glass fibers and a masterbatch comprising talc.

(7) The molding composition was injection molded into test samples. Isotropic E-modulus, tensile strength and elongation at break were determined. Results are summarized in Table I.

(8) Pellets Comprising Glass Fibers

(9) Pellets (glass filled pellets) were provided, comprising a core which comprises a multifilament strand, comprising glass fibers and an impregnating agent, and a sheath comprising a thermoplastic polymer. The pellets had a length of 15 mm.

(10) The multifilament strand comprising glass fibers was obtained from PPG Fiber Glass; LFT9000 (fiber diameter 19 μm, 4000 fibers/strand); amino silane sizing.

(11) The impregnating agent used was a blend of 40 wt % Vybar 260 supplied by Baker Hughes with 30 wt % of Microsere® 5981A and 30 wt % of Microsere® 5788A supplied by IGI.

(12) The thermoplastic polymer in the sheath was SABIC® PP579S propylene homopolymer with a MFI of 45 g/10 min (230° C./2.16 kg).

(13) Masterbatch Comprising Filler

(14) Pellets of a masterbatch comprising 70 wt % of a polymer and 30 wt % of an ultrafine talc filler were provided by using a ZE40/43D extruder; side feeder: house 4; vacuum in house 9. The compounding temperature was 210° C.

(15) The polymer used to prepare the masterbatch was SABIC® PP579S propylene homopolymer with a MFI of 45 g/10 min (230° C./2.16 kg). The ultrafine talc was HTP ultra5c (d50=0.45 um) supplied by IMI Fabi.

(16) The molding composition comprised comprising 64 wt % of polypropylene, 30 wt % of glass fibers and 1 wt % of talc. The remaining portion consisted of the impregnating agent and additives.

Examples 2-10

(17) Example 1 was repeated with different compositions of pellets and masterbatches to obtain the compositions summarized in Table 1. Results are summarized in Table I.

Comparative Experiment A-C

(18) Experiment A was performed as a comparative experiment for examples 1-3. The process described under Example 1 was repeated except that no masterbatch comprising the fillers was used. Experiment B was performed as a comparative experiment for examples 4-6. Experiment C was performed as a comparative experiment for examples 9 and 10. The compositions and the results are summarized in Table 1.

Example 11

(19) A molding composition comprising 45 wt % of glass fibers and 5 wt % of talc was prepared from pellets comprising glass fibers and talc. The molding composition was injection molded into test samples. E-modulus, tensile strength and elongation at break were determined. Results are summarized in Table II.

(20) Pellets Comprising Glass Fibers and Talc

(21) Pellets comprising talc filler in the sheath of thermoplastic polymer were prepared according to the following method.

(22) The glass fiber multifilament strand was obtained from PPG Fiber Glass. Type: LFT9000 (fiber diameter 19 μm, 3000 tex, 4000 fibers/strand); amino silane sizing. A blend similar to the blend disclosed in WO 2009/080281 being a blend of 30 mass % Vybar 260 (hyper-branched polymer, supplied by Baker Petro lite) and 70 mass % Paralux oil (paraffin, supplied by Chevron) was used as impregnating agent. The impregnating agent was melted and mixed at a temperature of 160° C. and applied to the continuous glass multifilament strands.

(23) The sheathing step was performed in-line directly after the impregnating step, using a 75 mm twin screw extruder (manufactured by Berstorff, screw UD ratio of 34), at a temperature of about 250° C., which fed a blend of the melted thermoplastic polymer and the ultrafine talc filler to an extruder-head wire-coating die having a die-hole of 2.8 mm. The line speed for impregnating and sheathing was 250 m/min.

(24) The thermoplastic polymer was SABIC® PP579S propylene homopolymer with a MFI of 45 g/10 min (230° C./2.16 kg).

(25) The ultrafine talc was HTP ultra5c (d50=0.45 um) supplied by IMI Fabi.

(26) The sheathed strand was cut into pellets of 12 mm length that were molded into test samples. The results are summarized in Table II.

Examples 12-15

(27) Example 11 was repeated with different compositions of pellets to obtain the compositions summarized in Table II. Results are summarized in Table II.

Example 16

(28) Example 11 was repeated using pellets comprising short glass fibers instead of talc particles.

(29) The short glass fiber was DS 2100-13P from 3B, fibre diameter 13 μm, fiber length 3-5 mm, amino silane sizing.

Example 17-18

(30) Example 1 was repeated using a masterbatch comprising short glass fibers instead of talc particles.

(31) The short glass fiber was DS 2100-13P from 3B, fibre diameter 13 μm, fiber length 3-5 mm, amino silane sizing.

(32) TABLE-US-00001 TABLE I Talc Filler in Masterbatch. Isotropic Isotropic Isotropic E- Tensile Elongation at Example or LGF Talc modulus strength break Experiment [wt %] [wt %] [MPa] [MPa] [%] A 30 0 3938 67.2 2.6 1 30 1 4034 66.0 2.4 2 30 10 4656 58.4 2.3 3 30 20 5460 56.1 2.0 B 40 0 4854 69.1 2.2 4 40 1 5045 66.2 1.9 5 40 10 5575 59.7 1.6 6 40 20 6290 52.7 1.4 7 45 5 5574 60.9 1.8 8 45 15 6223 51.8 1.4 C 50 0 5769 67.0 1.7 9 50 1 5861 63.3 1.5 10  50 10 6284 53.7 1.4 * The Long Glass Fiber (LGF) is the amount of glass fiber originating from the glass filled pellets.

(33) TABLE-US-00002 TABLE II Talc Filler in Sheath. Isotropic Isotropic Isotropic Elongation at Example or Talc size d50 LGF Talc E-modulus Tensile strength break Experiment (μm) [wt %] [wt %] [MPa] [MPa] [%] 11 0.45 45 5 5900.4 60.9 1.6 12 0.45 40 10 5843.2 57.5 1.6 13 0.45 30 20 5885.1 53.3 1.7 14 8 40 10 5801.6 56.4 1.6 15 1.5 40 10 5869.5 57.0 1.6

(34) TABLE-US-00003 TABLE III Short Glass Filler in Masterbatch or Sheath. Short Isotropic Isotropic Isotropic glass E- Tensile Elongation Example or filler modulus strength at break Experiment LGF [wt %] [wt %] [MPa] [MPa] [%] 16 Filler in 30 20 6103.9 68.3 1.8 sheath 17 Filler in 30 20 5822.9 62.7 1.6 masterbatch 18 Filler in 40 13.3 6120.4 63.6 1.5 masterbatch

(35) From the results it becomes clear that with both a talc filler and a short glass filler articles can be obtained wherein the material of the article has a high isotropic E-modulus. Favorable tensile strength and elongation break are also obtained.

(36) It is further shown that both a preparation process with the filler in the sheath and a preparation process with the filler supplied as a masterbatch gives good results for obtaining a material with a high Isotropic E-modulus.

(37) Higher isotropic E-modulus can be obtained with an increasing amount of the long glass fibers and the filler.

(38) Use of short glass fibers as the filler was found to give a higher Isotropic E-modulus than use of talc particles.